Electrical power-steering systems of the type referred to above are disclosed for example in DE 10 2008 021849 A1 and US 2005 0257992 A1. In these known solutions having two pinions and two electric motors associated thereto for actuating the rack member, the system is of a fail-safe type, since if one of the two electric motors is not in order the other motor ensures one half of the assist power. U.S. Pat. No. 4,741,409 discloses a device with two electric motors and two pinions that actuate two separate rack elements that are either completely independent from one another or are rigidly connected together in the case where one of the motors has a breakdown.